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CBSE Class 10 Answered

The first term of A.P. is 5 and the last term is 45.and the sum of all its terms is 400.Find the number of the terms and the common difference of the A.P.
Asked by Sanjusanjanna22 | 12 Sep, 2019, 23:59: PM
answered-by-expert Expert Answer
According to the question,
 
a = 5, last term = l = 45, Sn = 400
Sn = n/2 (a + l)
400 = n/2 (5 + 45)
solving we get n = 16
using t16 = 45
a + 15d = 45
5 + 15d = 45
d = 8/3
Answered by Sneha shidid | 13 Sep, 2019, 09:32: AM

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